The Multiaxial Creep–Fatigue Failure Mechanism of Mod. 9Cr-1Mo Steel Under Non-proportional Loading: Effect of Strain Energy on Failure Lives

2021 ◽  
Author(s):  
Fumio Ogawa ◽  
Yuta Nakayama ◽  
Noritake Hiyoshi ◽  
Ryuta Hashidate ◽  
Takashi Wakai ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Fatigue Failure ◽  
Strain Energy ◽  
Proportional Loading ◽  
Loading Effect ◽  
Creep Fatigue ◽  
Multiaxial Creep

Creep-Fatigue Strength of Sn-8Zn-3Bi Solder Under Multiaxial Loading

Materials ◽  
2005 ◽  
Author(s):  
Takaei Yamamoto ◽  
Takamoto Itoh ◽  
Masao Sakane ◽  
Hiroshi Sasaki ◽  
Kazuhiko Shuto ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Torsion Test ◽  
Multiaxial Loading ◽  
Strain Wave ◽  
Proportional Loading ◽  
Strain Waves ◽  
Creep Fatigue ◽  
Multiaxial Creep ◽  
Strain Hold

This paper describes the multiaxial creep-fatigue of Sn-8Zn-3Bi solder in proportional and non-proportional loadings. Push-pull and reversed torsion tests were carried in proportional test using fast-fast, slow-fast, fast-slow, slow-slow and strain-hold waves. Non-proportional tests were also carried out using box, step and circle strain waves. In proportional test, smallest creep-fatigue lives were observed in push-pull slow-fast test. Creep-fatigue lives in reversed torsion test were longer by a factor of 2 than those in push-pull test compared with the same strain wave. Non-proportional loading reduced the creep-fatigue life. Circle strain wave showed the smallest fatigue life in non-proportional loading. A non-proportional strain proposed by the authors correlated all the proportional and non-proportional fast-fast data within a factor of two scatter band.

scholarly journals Evaluation of Multiaxial Creep-fatigue Strength for High Chromium Steel under Non-proportional Loading

2019 ◽  
Vol 300 ◽  
pp. 07002
Author(s):  
Yuuki Kasamuta ◽  
Fumio Ogawa ◽  
Takamoto Itoh ◽  
Hiroyasu Tanigawa
Keyword(s):  
Chromium Steel ◽  
Fatigue Tests ◽  
Proportional Loading ◽  
High Chromium ◽  
Nuclear Fusion Reactor ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Strain Paths ◽  
Multiaxial Creep ◽  
Failure Life

This study discusses the result of creep-fatigue tests of a high-chromium steel, F82H which was designed as blanket structural materials of nuclear fusion reactor, carried out at room temperature to 823K in air. Strain paths applied were a push-pull loading and a circle loading in which normal and shear strain have 90 degree phase difference. The holding times used were 180 s and 600 s. Moreover, an evaluation of failure life by taking into account intensities of creep and non-proportionality is discussed based on both the life evaluation proposed by Itoh, et al and method of modified universal slopes. Availability of the equation for the life evaluation was confirmed by comparison with conventional universal slope method.

Creep-Fatigue Interaction Effects On Pressure-Reducing Valve Under Cyclic Thermo-Mechanical Loadings Using Direct Cyclic Method

2021 ◽  
Author(s):  
Nak-Kyun Cho ◽  
Youngjae Choi ◽  
Haofeng Chen
Keyword(s):  
High Temperature ◽  
Power Plant ◽  
Fatigue Failure ◽  
Material Properties ◽  
Structural Integrity ◽  
Direct Method ◽  
Element Model ◽  
Critical Loading ◽  
Creep Fatigue ◽  
Pressure Reducing Valve

Abstract Supercritical boiler system has been widely used to increase efficiency of electricity generation in power plant industries. However, the supercritical operating condition can seriously affect structural integrity of power plant components due to high temperature that causes degradation of material properties. Pressure reducing valve is an important component being employed within a main steam line of the supercritical boiler, which occasionally thermal-fatigue failure being reported. This research has investigated creep-cyclic plastic behaviour of the pressure reducing valve under combined thermo-mechanical loading using a numerical direct method known as extended Direct Steady Cyclic Analysis of the Linear Matching Method Framework (LMM eDSCA). Finite element model of the pressure-reducing valve is created based on a practical valve dimension and temperature-dependent material properties are applied for the numerical analysis. The simulation results demonstrate a critical loading component that attributes creep-fatigue failure of the valve. Parametric studies confirm the effects of magnitude of the critical loading component on creep deformation and total deformation per loading cycle. With these comprehensive numerical results, this research provides engineer with an insight into the failure mechanism of the pressure-reducing valve at high temperature.

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